This application claims priority to DE 101 36 861.5, a German patent application filed Jul. 27, 2001, pursuant to 35 U.S.C. xc2xa7119(a)-(d).
This invention pertains to charge air coolers for vehicles and more particularly to such charge air coolers that include a pre-cooler arranged in a collection tank of the charge air cooler.
Charge air coolers that have opposing inlet and outlet collection tanks fluidly connected by tubes that direct the charge air from the inlet tank of the charge cooler to the outlet tank of the charge cooler are known to include a second heat exchanger.
One example of such a charge air cooler is shown in DE 32 00 688 A1 in which the second heat exchanger consists of inflow and outflow coolant-filled lines (22, 23) with flat tubes or channels branching off these lines. The coolant-filled lines branching off of the inflow and outflow lines (22, 23) do not provide pre-cooling. Rather, these branched tubes are in parallel arrangement to air-cooled tubes and form a stacked construction alternating with the air-cooled tubes. Cooling of the charge air takes place by heat exchange between the charge air and cooling air of the charge cooler and also by heat exchange between the charge air and the coolant of the engine. This cooling method can allow a compact cooling system and easy adjustment to the varying loads of charge air supplied by the internal combustion engine. However, heat transfer may not be as efficient as desired and such charge coolers can be costly to manufacture and therefore have not been of significant use in practice.
A two-stage charge cooler is shown in DE 29 23 852 A. The first stage is a charge cooler that is cooled by the coolant of an internal combustion engine with the second stage being a charge cooler that is cooled by air and mechanically connected directly to the first stage charge cooler.
At least some charge coolers have exhibited short life spans due, at least in part, to the solder connections used in their manufacture because of temperature differences between the charge air and the cooling air or cooling liquid that do not occur in other types of heat exchangers in the vehicle field.
It is also known to arrange water-cooled heat exchangers, such as oil coolers or condensers, in a coolant collecting tank of coolant/air radiators to cool another fluid of the vehicle, such as oil or refrigerant. Such arrangements seek to utilize the cooling capacity of the engine coolant to satisfy other cooling demands of the vehicle, such as oil cooling or refrigerant condensing. Examples of such arrangements are shown in DE 198 20 412 A1 and EP 0 678 661 B1.
Looking forward, the exhaust limits of vehicles, particularly those with diesel engines, will place larger demands on heat exchanger manufacturers. The temperatures of the charge air exiting the charge cooler must be reduced much farther than in prior applications even though the charge air entering the charge cooler will have much higher temperatures than in prior applications. These conditions must preferably be met without requiring significantly larger design space for the charge air cooler.
In one form, the invention provides an air-cooled charge air cooler for vehicles. The charge air cooler has a pre-cooler oriented in an air collection tank of the charge cooler. The pre-cooler contains flow paths for a coolant and channels located between the coolant flow. The pre-cooler is sized to contact a majority of charge air flow entering the charge air cooler. The channels have a depth that allows for corresponding adjustment in the length of the cooling grate of the charge air cooler while maintaining the overall space requirement for the charge air cooler in a vehicle and meeting the increasing performance requirements of such charge air coolers.
In one form, the charge air cooler has an inlet collection tank on the opposite end from an outlet collection tank. A row of tubes fluidly connects the inlet and outlet tanks to direct a charge air flow from the inlet tank to the outlet tank. Heat exchange elements are arranged between the tubes to form a cooling grate through which a cooling airflow is directed. A pre-cooler is in the inlet collection tank and extends over a cross-sectional area of the inlet collection tank such that a majority of the charge air must pass through the pre-cooler. The pre-cooler has flow paths to direct a coolant flow therethrough and channels between the flow paths for charge air flow. The channels have a depth that is substantially perpendicular to the cross-sectional area of the inlet tank that is occupied by the pre-cooler and the depth is in a range of about 25 mm to about 200 mm.
According to one form, the channels have a depth in the range of about 40 mm to about 120 mm.
In one form, the flow paths of the pre-cooler are flat tubes. According to one form, the flat tubes extend in a perpendicular orientation relative to the tubes of the cooling grate.
In yet another form of the invention, a series of heat exchangers are arranged in a box-like array and one of these heat exchangers is an air-cooled charge air cooler including an inlet collection tank on the opposite end from an outlet collection tank. A row of tubes fluidly connects the inlet and outlet tanks and directs charge air from the inlet tank to the outlet tank. Heat exchange elements are arranged between the tubes to form a cooling grate through which a cooling airflow is directed. A pre-cooler is in the inlet collection tank and extends across a cross-sectional area of the inlet collection tank such that a majority of the charge air flow must pass through the pre-cooler. The pre-cooler has flow paths to direct a coolant flow therethrough and channels between the flow paths for the charge air flow. Each of the collection tanks extends roughly parallel and adjacent to a collecting tank of another of the series of heat exchangers to form an edge of the box-like array.
Objects and advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein and in the associated figures and appended claims.